Centrifugal fan



Det. 26 1926. I 1,604,328

G. H. WALKER CENTRIFUGAL FAN Filed May 20 I 1925 3 Sheets-Sheet l Oct. 26 1926. 1,604,328

G. H. WALKER CENTRIFUGAL FAN Filed May 20 I 1925 5 Sheets-Sheet 2 23 Hbb l lNvENTm-e` Oct. 26 1926. A1,604,328

Y G. H. WALKER CENTRIFUGAL FAN Filed May 20I 1925 3 Sheets-Sheet 5 fan provided with two Patented Oct. 26, 1926.

nutren' stares PATENT OFFICE.

GEORGE HENRY XVALKIER, OF WORCESTER, ENGLAND, ASSIGNOR TO HEENAN &:

- FROUDE LIMITED, OF MANCHESTER, ENGLAND.

CENTRIFU'GAL FAN.

Application led May 20, 1925, Serial No.

i absorbed by the fan.

According to the invention the impnllcr is surrounded by two discs eaeh having a hole or aperture in the centre so that when in position around the impeller they permit the latter to rotate while at the same time they enclose the flow of air between the two taces, the axial distance between the two discs being adjustable to vary the distance between their faces to regulate the amount of air or gas discharged by the tan.

The invention will be described with reference to the acconipanyinodrawings.

Fig l is a front elevation showinpr the fan coupled to an engine mounted on a torque reaction bench. l

Fig. 2 is a longitudinal section through adjustable discs.

lig. 3 is a section on line 3-3 Fig. 2.

Fig. 4; is a section on line 4-4 Fig. 2.

Fig. 5 is a longitudinal section through a fan provided with one adjustable disc.

Fig. G is an end view of same.

Fig. 7 is a perspective view ot adjustable disc.

Fig. 8 is an enlarged sectional view of adjustable discs shown in Fig. 5.

Fig. 9 is an enlarged sectional view of adjustable discs shown in Fig. 5.

ln the form of the invention shown in Figs. 2, 3, Ll and 8 the impeller A, which is of the double inlet centrifugal fan type. is surrounded by two axially adjustable discs B1, B2 each provided with a hole or aperture in the centre slightly larger in diameter than the diameter ot the impeller A. Each disc B1 B2 is mounted on a large tube C1 C2 of the same internal diameter as the aperture in the discs B1 B2 so that when in position around the impeller A they permit the latter to rotate while at the same time they enclose the flow of air or gas between the :faces of the two dises B1 B2.

The axial distance between the discs B1 B2 is adjustable to vary the distance between them to regulate the amount oi air or gas discharged by the impeller A.

The large tubes C1 C2 are formed to slide in annular rings@1 c2 provided at the ends lto.

31,679, and in Great Britain July 1, 1924.

with strips or 'rings c of felt or other suitable packing to prevent the escape of air or gas'through the rings. Valances D1 D2 surrounding` the sides `of the impeller A are the rings c1, c2 holes al being formed therein for the passage of the air or gas. These valances Dl D2 serve with the large tubes C1 (J2 to venclose the impellcr A and prevent or .permanently attached to the inner-ends of minimize the setting` up of eddy currents thereby decreasing the useless vot power by such currents.

The adjustment of the discs B1 B2 made by means ot' a number ot' right hand other suitable gearing o2 and universal coupling b3 trom a hand wheel b* or other suitable means either by hand or automatically. As shown in Fig. l the hand wheel is consumption may be and left screwed rods b1 operated by a Ichain or 70 preferably arranged adjacent to the other control members on the torque reaction bench E being connected through a shaft e and flexible coupling e1.

To relieve the screwed rods b1 ing moment they spherically seated nuts o5, b carrying re. spectivelj,7 the discs B1 B2 and which transmit the thrust ot the screwed rods 1 there- The nuts' ZJ b are prevented from roof any bendpreferably engage with two '80 tating by any suitable means and as they are a5 located axially by their spherical seatings, it follows that rotation of the screwed rods b1 throutrh the gearing b2 and universal couplinp; o3, will cause the nuts to travel in opposite directions along the screwed rods, en

and thus control tbe axial position of the discs B1 B2 and the large tubes C1 C2. Other means of axial adjustment of the discs b1 Z22 and large tubes C1 C2 may however be adopted but the means described' above is that e5 which is at present preferred The weigl'it of the dises B1, B2 and ot the large tube C1, C2 is preferably carried by rollers 717 runningon a tixed track or rails b.

lVith a tan ot the double inlet type it is necessary to construct one side of the casing A1 with a number of air passages a cornmunicating from the external atmosphere to the suction eye of the impeller A on the same side.

These passages o radiate outwardly from the axis ot the impeller shaft, and the spaces between them torni intermediate passages a1 for the air or gas discharged by the impeller A. By enclosing these spaces with lll plates a3 the air or gas may be conveyed to a position near the axis of the impeller shaft, from which it may be caused to emerge through suitable wind straighteners at, and the resulting blast may be put to any useful purpose.

The various orifices, ducts and passages and the surrounding plates may be replaced by ducts of other shape and the casing A1 may be of volute or other shape as desired. Where the casing A1 is of volute form the air. or gas has a free ingress to both suction eyes of impeller A, and the air orgas discharged may be conducted to any desired point.

ln the form of the invention shown 1n Figs. 5, 6 and 9 only the disc B1 is mounted with the tube C1 so as to be adjustable longitudinally, the other disc B2 being permanently attached to the impeller casing A1. In this construction the screwed rods b1 are provided with spherical heads b9 non-rotatably connected with the sliding disc B1 and engaging with a. nut Z210 held rotatably in a spherical seating Z211 iixed to the impeller casing A1. rlhe rotation of the nut Z210 by means of the gear wheel Z22 controls the axial position of the disc B1 and large tube C1. Figs. 5 and 6 show a fan of the single inlet type the air or gas entering the eye of the impeller from one side only.

In both constructions shown the distance between the faces ot discs B1 B2 when they are widest apart corresponds with the eiiective width of the impeller A, and in this position the amount ot air or gas discharged is a maximum, but when they are brought close together the amount of air or gas discharged is a minimum, and may by suitable design be made practically zero.

The discs B1 B2 are of slightly conical tormation so that the annular' space between them at a point close to the impeller A is narrower than at the outer diameter of the discs. rlhus the air or gas on leaving the impeller and entering the annulus between the discs, is flowing at maximum velocity, but is slowed down gradually during its passage to the outer diameter of the annulus. rllhereby the kinetic energy of the air at the impeller discharge is to a large extent recovered in the form ot' pressure at the outer diameter of the annulus.

A centrifugal fan constructed in accordance with the above description is particularly suitable for use as an air brake, in conjunction with a torque reaction bench or cradle, when absorbing and measuring the power developed bv an internal combustion engine. or other prime mover.

What l claim as my invention and dcsire to protect by Letters Patent is:-

l. ln a centrifugal Ylan of the type reiferrcd to the combination with the impeller of a tube slightly larger in diameter than the impeller, means for moving the tube axially whereby the tube may be moved from the position where the impeller is unmasked through any intermediate position to the position where the impeller is completely masked, a divergent disc mounted on the inner end or' said tube and a second divergent disc at the opposite side of the impeller, the gas escaping trom the impeller between the two discs so that its velocity will he gradually slowed down and the kinetic energy of the gas at the impeller discharge will be recovered in the form of pressure. 'l

2. In a centrifugal fan of the type referred to the combination with the impeller or' a tube slightly larger in diameter than the impeller, means for moving the tube axially whereby the tube may be moved from the position where the impeller is unmasked through any intermediate position to the position where the impeller is completely masked, a divergent disc mounted on the inner end of said tube, a hollow ring in which the tube slides, and a second divergent disc at the opposite side ot' the impeller, the gas escaping from the impeller 'between the two discs so that its velocity will be gradually slowed down and the kinetic energy of the gas at the impeller discharge will be recovered in the orm of pressure.

3. In a centrifugal fan of the typea referred to the combination with the impeller of a tube slightly larger in diameter than the impeller, means tor moving the tube axially whereby the tube may be moved from. the position where the impeller is unmasked through any intermediate position to the position where the impeller is completely masked, a hollow ring in which the tube slides, a divergent disc mounted on the inner end of said tube, a second divergent disc at the opposite side ot' the impeller, the gas escaping from the impeller between the two discs so that its velocity will be gradually slowed down and the kinetic energy of the gas at the impeller discharge will be ren covered in the form of pressure, a casing around the impeller and passages in said casing to direct the gas in a direction parallel to the axis of the impeller and deliver it adjacent to a prime mover driving the impeller.

4l. ln a centrifugal fan of the type relerred to thi` combination with the impeller ol' a tube slightly larger in diameter than the impeller, a second tube ot the same diameter as the iirst tube, arranged atthe other side olI the iinpeller, a hollow ring in which the iirst tube slides, a second hollow ring in which the other tube slides, means for moving the tubes axially whereby they may be moved from the position where the impellcr is unmasked through any inter mediate position, to the position where the impcller is completely masked, a divergent disc mounted on the inner end of the first tube, a second divergent disc mounted 0n the end of the second tube, the gas escaping from the impeller between the two discs so that its velocity will be gradually slowed down and the kinetic energy of the gas. at the impeller discharge will be recovered in the form of pressure, a casing around the 10 impeller and passages in said casing to direct the gas in a direction parallel to the axis of the impeller and to a prime mover drivingr the impeller.

In testimony whereof I my hand.

GEORGE H. WALKER.

deliver it adjacent e have hereunto set 15 

